Spectroscopic and first-principles investigations of iodine species incorporation into ettringite: Implications for iodine migration in cement waste forms

Guo, Binglin; Xiong, Yihuang; Chen, Weinan; Saslow, Sarah A.; Kozai, Naofumi; Ohnuki, Toshihiko; Dabo, Ismaïla; Sasaki, Keiko

doi:10.1016/j.jhazmat.2019.121880

Cited by 52 publications

(14 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 8 presents XRD patterns of non-cement blended samples prepared using various S/FA ratios at 28 days. Hydration products appeared in various phases, including Ca(OH) 2 , Ca [31] peaks compared to the control groups. Note that the non-cement blended specimens also presented relatively small Ca(OH) 2 peaks and slightly high Ca 3 SiO 5 peaks compared to the P specimens.…”

Section: Drying Shrinkagementioning

confidence: 87%

“…Hydration products appeared in various phases, including Ca(OH)2, Ca3SiO5, Ca6Al2(OH)12(SO4)3-26H2O and CaFe2O5. The non-cement blended specimens displayed roughly the same CaSO4-2H2O and Ca6Al2(OH)12(SO4)3-26H2O (ettringite) [31] peaks compared to the control groups. Note that the non-cement blended specimens also presented relatively small Ca(OH)2 peaks and slightly high Ca3SiO5 peaks compared to the P specimens.…”

Section: Drying Shrinkagementioning

confidence: 87%

See 1 more Smart Citation

Composite Properties of Non-Cement Blended Fiber Composites without Alkali Activator

Lin

Korniejenko

et al. 2020

Materials

View full text Add to dashboard Cite

The vigorous promotion of reuse and recycling activities in Taiwan has solved a number of problems associated with the treatment of industrial waste. Considerable advances have been made in the conversion of waste materials into usable resources, thereby reducing the space required for waste storage and helping to conserve natural resources. This study examined the use of non-alkali activators to create bonded materials. Our aims were to evaluate the feasibility of using ground-granulated blast-furnace slag (S) and circulating fluidized bed co-fired fly ash (F) as non-cement binding materials and determine the optimal mix proportions (including embedded fibers) with the aim of achieving high dimensional stability and good mechanical properties. Under a fixed water/binder ratio of 0.55, we combined S and F to replace 100% of the cement at S:F ratios of 4:6, 5:5, 6:4. Polypropylene fibers (L/d = 375) were also included in the mix at 0.1%, 0.2% and 0.5% of the volume of all bonded materials. Samples were characterized in terms of flowability, compressive strength, tensile strength, water absorption, shrinkage, x-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. Specimens made with an S:F ratio of 6:4 achieved compressive strength of roughly 30 MPa (at 28 days), which is the 80% the strength of conventional cement-based materials (control specimens). The inclusion of 0.2% fibers in the mix further increased compressive strength to 35 MPa and enhanced composite properties.

show abstract

Section: Drying Shrinkagementioning

confidence: 87%

Section: Drying Shrinkagementioning

confidence: 87%

Composite Properties of Non-Cement Blended Fiber Composites without Alkali Activator

Lin

Korniejenko

et al. 2020

Materials

View full text Add to dashboard Cite

show abstract

“…Possible sorption sinks in cement include aluminoferrite monosulfate, ettringite (aluminoferrite trisulfate), and calcium-silicate-hydrate phases. For sorption onto aluminoferrite monosulfate and ettringite, I /IO3substitutes for SO4 2 (Aimoz et al, 2012a;Aimoz et al, 2012b;Atkins and Glasser, 1992;Gillispie et al, 2020;Guo et al, 2020;Reigel and Hill, 2016). Using X-ray absorption fine structure (EXAFS), Guo et al (2020) showed that minimal Iwas incorporated into ettringite (0.05%), whereas IO3exhibited a high affinity for ettringite via anion substitution for SO4 -(96%).…”

Section: I and 99 Tc Desorption From Uhpgmentioning

confidence: 99%

“…For sorption onto aluminoferrite monosulfate and ettringite, I /IO3substitutes for SO4 2 (Aimoz et al, 2012a;Aimoz et al, 2012b;Atkins and Glasser, 1992;Gillispie et al, 2020;Guo et al, 2020;Reigel and Hill, 2016). Using X-ray absorption fine structure (EXAFS), Guo et al (2020) showed that minimal Iwas incorporated into ettringite (0.05%), whereas IO3exhibited a high affinity for ettringite via anion substitution for SO4 -(96%). Bonhoure et al (2002) used I K-edge X-ray absorption spectroscopy to demonstrate that calcium-silicate-hydrate phases was not an especially important uptake-controlling phase for IO3 .…”

Section: I and 99 Tc Desorption From Uhpgmentioning

confidence: 99%

Ultra-High-Performance Grout for Encapsulation of HEPA Filters

Nichols¹

2021

View full text Add to dashboard Cite

Ultra-high-performance grout (UHPG) grout appears to be good candidate for solidification and encapsulation of waste containing 99 Tc and 129 I that benefits from low Dobs. The properties that make UHPG a good candidate for encapsulating HEPA filters would make it a good option for microencapsulating other solid secondary waste (SSW) such as granular activated carbon, silver mordenite, and ion exchange resins. Containers made of UHPG would also be good candidates for dry disposal of SSW due to its very low diffusivity which prevents contaminant migration. Contaminated high-efficiency particulate air (HEPA) filters will be generated during operation of the secondary off-gas treatment system in the Low Activity Waste (LAW) Facility of the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The HEPA filters receive off-gas from the vessel vent header and primary off-gas treatment system in LAW Facility and remove particulate contaminants including 99 Tc and 129 I salts. The current disposal method for HEPA filters is encapsulation in metal containers using grout and placement in the Integrated Disposal facility (IDF), (Nichols et al., 2017). Results from calculations supporting the IDF Performance Assessment (PA) demonstrated that contaminated HEPA filters from the WTP are the largest contributors to groundwater impacts and dose to a member of the public in the future from contaminants of potential concern (CoPC), including 129 I and 99 Tc. 129 I Kd, mL/g 110 110 Rf 517 1600 Dobs, m 2 /s 3.2 x 10-13 1.7 x 10-19 Deff, m 2 /s 1.7 x 10-10 2.7 x 10-16 Note: a insufficient spike in Baseline grout to measure Kd, b not solubility controlled in Baseline grout, c solubility controlled in UHPG.

show abstract

“…For example, ettringite, commonly formed in CASH cements, has been shown to incorporate RCRA metal and radionuclide cations and anions into its structure (Gougar et al 1996). In more recent studies, ettringite has been proposed as a natural pathway for immobilizing COCs to the Hanford Site TcO4 -, as well as IO 3 and CrO 4 2- (Aimoz et al 2012a;Aimoz et al 2012b;Um et al 2017;Guo et al 2020). Given the mineralogical evolution of the cement matrix as cementitious waste forms age, the ability to facilitate controlled early mineral formation through long-term mineral growth could provide a valuable pathway towards integrating a natural contaminant barrier into these waste forms.…”

Section: Line 9 -Mineral Incorporationmentioning

confidence: 99%

Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Skeen

Langston

McCabe

et al. 2020

View full text Add to dashboard Cite

An expert panel consisting of the document authors was assembled by Washington River Protection Solutions, LLC (WRPS) and tasked with (1) identifying technical and regulatory limitations to treating and disposing of grouted low-activity waste (LAW), and (2) with identifying and evaluating a wide range of technical solutions to these limitations. The analysis included technologies to allow inventory management and/or improve retention of iodine, technetium, and nitrate either in the waste packages, or within the Integrated Disposal Facility (IDF), and, technologies to ensure regulated organics are below Resource Conservation and Recovery Act of 1976 (RCRA) Land Disposal Restriction (LDR) levels.The expert panel completed their analysis in three distinct phases. In Phase I, the team reviewed the chemical and physical characteristics of the most recent projected supplemental LAW (SLAW) feed vector along with disposal site waste acceptance criteria and the fiscal year 2019 results from Pacific Northwest National Laboratory that identified the level of improvement that would be needed to meet onsite disposal requirements in the IDF (Asmussen et al. 2019a). The two regulatory constraints targeted for technology solutions by the expert panel were (1) current estimates based on performance assessment fate-andtransport modeling indicate that if the entire quantity of LAW currently designated for supplemental treatment were solidified as a cementitious material, nitrate, 99-Tc, and 129-I could exceed groundwater standards after DOE's time of compliance (1,000 years) but within 10,000 years after IDF closure and (2) LAW may contain RCRA LDR organics at levels that require removal to meet LDR concentration-based limits. It should also be noted that the first issue is only applicable to on-site disposal, not offsite at WCS and is based on calculations that assume either a low-performing grout is used, or high-performance grout does not maintain its performance (SRNL-RP-2018-00687). Asmussen et al. (2019a) estimated that the inventory of grouted SLAW could meet IDF groundwater requirements if the release rate of nitrate, 99-Tc, and 129-I were reduced by a factor of approximately 3.2, 10, and 32, respectively versus baseline formulation performance.In Phase II, an extensive list of technologies and engineering approaches was identified and subjected to an initial assessment by the group. Current knowledge associated with technology maturation needs and constraints to implementation at Hanford were recorded in 13 distinct categories. In the final phase of the process (Phase III), the expert panel selected 7 of the 13 categories for qualitative rating and a series of meetings were held between the expert panel to discuss and rate each technology in each category. All ratings were developed by consensus. After the qualitative rating was complete, a numerical scoring criterion for each category was applied and a composite score for the individual technologies was calculated. An uncertainty score was also developed for each technolo...

show abstract

Spectroscopic and first-principles investigations of iodine species incorporation into ettringite: Implications for iodine migration in cement waste forms

Cited by 52 publications

References 55 publications

Composite Properties of Non-Cement Blended Fiber Composites without Alkali Activator

Composite Properties of Non-Cement Blended Fiber Composites without Alkali Activator

Ultra-High-Performance Grout for Encapsulation of HEPA Filters

Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Contact Info

Product

Resources

About